/Engine/Source/Runtime/GeometryCore/Public/Implicit/SparseNarrowBandMeshSDF.h
a grid that can be sampled within the narrow band to find the ID of the closest triangle. Note: this is populated duringCompute()
const [FBlockedGrid3i](API\Runtime\GeometryCore\Spatial\FBlockedGrid3i) & GetClosestTriGrid() const